Near-field communications (“NFC”) is a short-range wireless technology that allows detection and communication between powered active “initiator” devices and non-powered passive “target” devices. A passive target device is typically a very small sticker with no connected power source. Passive target devices receive power from a radio frequency (“RF”) field from an initiator device. Upon receipt of an RF field, the passive target device establishes a transponder relationship with the initiator device, and the passive target device can transmit information to the initiator device.
One of the benefits of NFC is also a limiting attribute. NFC target devices are able to obtain power from other devices. Because NFC target devices are not powered, NFC target devices can be small, simplistic in architecture, and can therefore be placed upon just about any object. Unfortunately, NFC target devices are unable to transmit information, reveal proximity, or otherwise be known by nearby initiator devices that are not transmitting an RF field. Mobile initiator devices, such as NFC-enabled smartphones, typically have limited battery power, and for this reason, cannot transmit an RF field continuously. Mobile initiator devices therefore activate an RF field only when manually selected by a user. For example, a user may select an NFC activation button on a peer-to-peer application to activate the RF field.